I had the chance to put some of my own thoughts on paper about Glass's symphonies, as those thoughts stand now, when I wrote a chapter of a proposed book about Glass's music this past year. The resulting 50 pages were then adapted to become 41 pages of liner notes which are included in the digital download of the symphony box on iTunes and can also be Here.

Unlike Glass's string quartets which follow a linear progression in terms of becoming deeper and more involved musically, the Glass symphonies represent a much greater variety of experience. The First and Fourth Symphonies are based on music not originally composed by Glass. The Third Symphony is a symphonic chamber work. The Fifth, Sixth, and Seventh Symphony are all programmatic in some way. Only the Second, Eighth, Ninth and Tenth are purely instrumental works.

I was informed last week that Glass is currently composing his Eleventh Symphony, which if you read my liner notes, you can imagine will be cast in the type of discourse which began in the Second, continued in the first movement of the Seventh and in the entire Eighth, and came to full realization in the Ninth. Of course we know now that the Tenth was composed before the Ninth, and wasn't conceived of originally as a symphony at all.

Considering the shape and proportions of the Eighth (movements of 19, 12, and 7 minutes respectively) I speculated that combined with time pressures, that the Eighth organically "got away" from Glass, its composition taking him to its own destination at the expense of any preconceived plan. In that way it became Glass's "unfinished" symphony. I consider the Tenth to be in reality No.8.5 in that it was composed in 2007 and only orchestrated in 2012 to become the "Not-Nine" Symphony, a sort of anti-Ninth. That symphony was seemingly predestined in Glass's mind to provide contrast to the big serious statements of Nos. 8 & 9.

In interviewing Glass, the composer stated that in writing as many symphonies as he has, he now has a personal expectation when facing the proverbial blank page at the outset of a symphony. More interesting are how Glass's recent music has changed very rapidly.In the past Glass has said that the process of perceiving real changes in his music usually take place over a 10 year period. Perhaps starting a few years ago in pieces like "Four Movements for Two Pianos" we see a sort of hyperactive and impatient thread appear in Glass's music.

Less progressive yet thrilling Glass pieces like the Concert Overture (2012) were still part of his output. However we begin to see frantically almost funky pieces like the Double Piano Concerto, The Lost, and the Sixth String Quartet become the new norm. These pieces are most easily described as busy, dense, full of constant change and full of thick layers. So it will be very interesting to see how Glass reconciles his own personal expectation on how his new major symphony will turn out with his very recently discovered new musical language.

In the meantime, for those in London and Scotland this weekend you'll get to hear Glass's latest ideas about what a Symphony could be. For the rest of us we can meditate on the already bold and varied body of work contained in the box set.